Various paper handling systems are designed to process a wide variety of media items. These media items may be of various sizes and shapes and of various types of materials and documents. For example, if the media items are envelopes, to accommodate and process a volume of items, the envelope may be shingled in a shingle feed tray. However, if the items are sheets, such as 8½×11 paper, to accommodate and process a volume of sheets, the items may be stacked in a stacks feed tray. When these media items are moved from the shingle or stacks feed tray into the feeder mechanism, as the case may be, the items are separated from the other media in the tray for processing in the system.
To obtain reliable media item separation in the separation operation, the input mechanism of existing media handling systems are limited to specific media geometry due to a number of compromises that must be made in the presentation of the media items to the feeder. The optimal presentation of the media to the separator is a complex problem that is constrained by the geometry of the media being fed, the form of separator, the desired form of human interaction with the system, the control of the stack force during feeding, and other factors.
In certain inserter products, for example, all media items are fed from a shingled stack of items. This is a logical set up and orientation for short media items such as ⅓ to ½ document length (such as 8½×11 inches) media items, including trifold media items, envelopes, and small booklets. The format is cumbersome for sheets, such as 8½×11 inch sheets of paper. The conflicting angles at which the various media (stacked sheets vs. shingled envelopes) advance down the tray can cause wide variations in stack normal force and compromise the feeder's ability to separate the media. Accordingly, separate input points with feeder mechanisms or the need for operator intervention to change the feeder mechanism for the type of feed tray, shingle or stacks, and the type of media, are frequently employed.